[Bill]

Tom, Do you unplug your block heater before heading down the road? I know it’s not necessary, but is there a downside leaving the block heater plugged in when in cold weather or do you plug/unplug everytime you start up. Also, do you shut off the valve to the engine from the Webasto to isolate it to save on diesel or is that not applicable in our vintage Marathon?

[Archived]

Block heaters are typically controlled at the coach 120V circuit breaker panel, although Marathon may have done it differently. They are not going to be run through inverters, but likely are only on if the main CB is on, and the coach is on generator or shore power.

You should not have to unplug them unless you want to use the outlet for something else but you should turn off the 120V circuit breaker when it is not needed. If you are in cold country and don’t have an Aquahot or Webasto to keep you warm at night you may want to leave it on. But if you aren’t remaining in cold country it makes no sense to have it on heating up the engine.

[Reagan]

American Coach wired my block heater through the inverters, along with everything else in the bus. I keep the block heater unplugged so I don’t accidentally turn it on and discharge my batteries. I mention this because there are a few other American Coach owners on P.C.

[Archived]

I have two outlets in the engine compartment. One is up high, center coach, above the doors. That is the one my engine block heater plugs into. The second is by the air filter and batteries. They are on the same breaker inside. Since I use the second plug when working on the bus, vacuuming the car, charging the batteries or whatever, I usually leave the block heater unplugged.

This time of year when I am more likely to need the block heater than I am to be using the second outlet, I leave it plugged in. When it is under 40 degrees and I am traveling the next day, i just flip the breaker inside. Like Bryan, mine is wired through the inverters like everything else on the coach (Vantare) so I am careful with the position of the breakers at all times..

Davy

[Rudy]

Tim,

I leave the block heater unplugged just to be sure since CRS can happen at any time and I might forget to turn off the breaker.

Also, do you shut off the valve to the engine from the Webasto to isolate it to save on diesel or is that not applicable in our vintage Marathon?

I don’t understand what you’re asking.

[Archived]

I leave block heater unplugged when not in use.

[AL]

Tom,

I think you are being asked —

“Do you use the Webasto to heat the coach, hot water AND the engine ALL the time? OR, do you take the engine out of the heating loop WHEN you are sitting and not traveling?”

The big engine block which sits open to cold air can and does remove a good amount of the heat in the coolant put there by the Webasto burning diesel fuel. So, those that can isolate the engine from the heating loop when sitting can save some diesel fuel by allowing the burner to cycle off more often.

[Bill]

The miniscule amount of fuel saved by not heating the engine can’t even be calculated.

My Marathon does not heat the engine with Webasto unless the button at the dash “Block Heater” is turned on. But, the engine does get some heat while sitting and the Webasto is being run for coach heat and hot water. It’s not really a closed loop for the engine, so it gets heated normally. You could turn off the engine heat loop, but why bother.

Tim – To verify this, when running your Webasto next time for heat, go back and feel the engine coolant lines, they will be warm.

Some of the Conversions heat the engine with the Webasto running period.

[Archived]

Yes Tom, My question was asking what Peter and then Rudy later clarified, if it’s worth taking the engine out of the Webasto loop when sitting and not traveling. From your come t it doesn’t seem worth it. But I looked they the various compartments and couldn’t find the shut off even if I wanted to isolate it. Unless the Webasto only flows thru the engine when you press the block heater button on the panel, then it makes it easy.

[Archived]

I’m interested in whether others treat the coolant isolation valves as ‘for emergency use only” like I do, or whether you routinely exercise them to make sure they are working. The only time I ever touched one on my prior bus it immediately started leaking and I had to spend a messy hour and half on the repair. Since then I’ve never touched one.

[Archived]

Never touch them. Never thought about it.

After you asked the question it made me think about the merit of leaving them open or closed and only turning the valve as needed.

First I had to think about how my system is set up. I have a loop through the house. I have a loop through the HW tank and bay heater, and of course the engine loop going through the Webasto and circulating pump. I always want hot water when we are in the coach so except for service or to shut off a leak I want that valve open. I suppose I could consider leaving the house loop valves open that might circulate heat into the house on a hot day, but the circulating pump is not on when I don’t call for heat so the small amount of circulation if any is overcome by the A/C whether driving or parked so I don’t need to touch that valve, and that concern goes away as the engine cools. That leaves the engine loop through the Webasto. If I need the Webasto, unless I am staying in sub freezing weather for a long time and am concerned about fuel use I guess I might turn the loop off, but that is unlikely.

So I’m with Bryan for reasons that don’t relate to a potential valve leak, although that is just one more reason to not shut off the coolant circulation valves.

[Archived]

I turn the coolant loop off in the summer, that way if the blend valve lets a little coolant through while running the A/C it won’t degrade the cold air.

[Archived]

I turn the hot water tank and water bay heat exchanger loop off in the summer and leave all other loops open, unless my wife is with me , then I leave all loops open , so there is hot water when going down the road or right when we stop,

[Darrell]

Don’t mix up apples and oranges. I suspect for those unaware there are a couple of coolant loops, one being the converter installed and the second being the original Prevost installed. If I am not mistaking Truk is talking about the Prevost coolant loop going to the heat exchanger for driver’s air. On OTR equipped coaches there is a similar counterpart on the whole coach heat exchanger also.

My answer dis not address this, but I leave those loop valves untouched also.

[Tim]

Jon and Tom (or anyone knowing),

I wouldn’t mind turning off the ‘heat loop’ during the summer. Is that easy to do?

Thanks,

Mark